The present invention is directed to solid inorganic polymers having organo groups anchored to the surfaces of the polymers. The majority of the polymers formed are layered crystals which display intercalation activity.
The interface surfaces of solids, whether amorphous, crystalline, or semicrystalline, are responsive regions of chemical and physical action. In many practical chemical and physical phenomena, such as absorption, corrosion inhibition, heterogeneous catalysis, lubrication, ion exchange activity, adhesion and wetting and electrochemistry, activity occurs as a consequence of the presence of a definable solid surface.
Many inorganic solids crystallize with a layered structure and some could present sites for anchoring active groups. In this form, sheets or slabs with a thickness of from one to more than seven atomic diameters lie upon one another. With reference to FIG. 1, strong ionic or covalent bonds characterize the intrasheet structure, while relatively weak van der Waals or hydrogen bonding occurs between the interlamellar basal surfaces in the direction perpendicular to their planes. Some of the better known examples are prototypal graphite, most clay minerals, and many metal halides and sulfides. A useful characteristic of such materials is the tendency to incorporate "guest" species in between the lamella.
In this process, designated "intercalation," the incoming guest molecules, as illustrated in FIG. 2, cleave the layers apart and occupy the region between them. The layers are left virtually intact since the crystals simply swell in one dimension, i.e., perpendicular to the layers. If the tendency to intercalate is great, then the host-layered crystal can be thought of as possessing an internal "super surface" in addition to its apparent surface. In fact, this potential surface will be greater than the actual surface by a factor of the number of lamella composing the crystal. This value is typically on the order of 10.sup.2 to 10.sup.4. Although edge surface is practically insignificant compared to basal surface, it is critical in the rate of intercalation, since the inclusion process always occurs via the edges. This is because bonding within the sheets is strong and, therefore, basal penetration of the sheets is an unlikely route into the crystal.
In graphite, the function of the host is essentially passive. That is, on intercalation, the host serves as the matrix or surface with which the incoming guest molecules interact, but throughout the process and on deintercalation the guests undergo only minor perturbation.
In order for a more active process to occur during intercalation, such as selective complexation of catalytic conversion, specific groups must be present which effect such activity.
An approach in which catalytically active agents have been intercalated into graphite or clays for subsequent conversions has been described in "Advanced Materials in Catalysis," Boersma, Academic Press, N.Y. (1977), Burton et al, editors, and "Catalysis in Organic Chemistry," Pinnavia, Academic Press, N.Y. (1977), G. V. Smith, editor.
One of the few layered compounds which have potential available sites is zirconium phosphate, Zr(O.sub.3 POH).sub.2. It exists in both amorphous and crystalline forms which are known to be layered. In the layered structure, the site-site placement on the internal surfaces is about 5.3 A, which leads to an estimated 25 A area per site. This area can accommodate most of the functional groups desired to be attached to each site. The accepted structure, symbolized projection of a portion of a layer of this inorganic polymer and a representation of an edge view of two layers, are shown respectively in FIGS. 3, 4 and 5.
Besides the advantageous structural features of zirconium phosphate, the material is chemically and thermally stable, and nontoxic.
Quite a bit of work has been conducted on the zirconium phosphate, mainly because it has been found to be a promising inorganic cation exchanger for alkali, ammonium and actinide ions, Alberti, "Accounts of Chemistry Res." 11, 163, 1978. In addition, some limited work has been described on the reversible intercalation behavior of layered zirconium phosphate toward alcohols, acetone, dimethylformamide and amines, Yamaka and Koisuma, "Clay and Clay Minerals" 23, 477 (1975) and Michel and Weiss, "Z. Natur," 20, 1307 (1965). S. Yamaka described the reaction of this solid with ethylene oxide, which does not simply incorporate between the layers as do the other organics, but rather was found to irreversibly react with the acidic hydroxyls to form a covalent bonded product, Yamaka, "Inorg. Chem." 15, 2811, (1976). This product is composed of a bilayer of anchored ethanolic groups aimed into interlayers. The initial layer-layer repeat distance is expanded from about 7.5 A to 15 A, consistent with the double layer of organics present. The overall consequence of this reaction is to convert inorganic acid hydroxyls to bound organic alkanol groups.
A very recently reported effort in the field is Alberti, et al., "J. Inorg. Nucl. Chem.," 40, 1113 (1978). A method similar to that of this invention for the preparation of zirconium bis(benzenephosphonate), zirconium bis(hydroxymethanephosphonate) monohydrate, and zirconium bis(monoethylphosphate) is described, with descriptions of the properties for these products.
Following the Alberti publication, a paper by Maya appeared in "Inorg. Nucl. Chem. Letters," 15, 207 (1979), describing the preparation, properties and utility as solid phases in reversed phase liquid chromatography for the compounds Zr(O.sub.3 POC.sub.4 H.sub.9).sub.2.H.sub.2 O, Zr(O.sub.3 POC.sub.12 H.sub.25).sub.2 and Zr(O.sub.3 POC.sub.14 H.sub.21).sub.2.
All of the compositions described herein can be useful in gas phase, liquid phase, gas liquid, reversed phase, and bulk and thin layer chromatography. The compounds can also be useful as hosts and carriers for organic molecules and especially biologically active organic molecules. They are also useful as catalysts or as supports for catalysts. For example, they can be used in an analogous fashion to the compositions which are discussed by Bailar, "Heterogenizing Homogeneous Catalysts," Catalysis Reviews--Sci. & Eng., 10(1) 17-35 (1974) and Hartley and Vezey, "Supported Transition Metal Complexes as Catalysts," Advances in Organo-metallic Chemistry, 15, 189-235 (1977).